"Shut up, that's why" is the name given by author and blogger Greta Christina to a category of rhetorical tactics aimed not at countering atheists' arguments, but at stopping argument altogether. While some of them are logical fallacies, others are not even structured well enough to qualify as logical fallacies.

Rhetorical tactics

Christina identifies several tactics that fall into this category:

Why talk about about atheism when there are much bigger problems in the world?

Religion is not in the same category as science and politics, and should not be expected to prove itself the same way (aka non-overlapping magisteria).